Eye bolts in which the supporting bolt in the form of a threaded stem is secured in one piece to the lifting eye and, by rotating them, can be screwed into a receiving hole of an item to be coupled are known and standardized e.g. by DIN 580. Although these known eye bolts can be installed or removed without an additional tool, they have the disadvantage that they cannot be aligned in the direction of load and thus, when they are used, either they cannot be screwed in fully or may become unscrewed. With such eye bolts designed as one piece, there is always the danger that the threaded stem will be overloaded or loosened by a torque acting on the lifting eye, which can result in the threaded bolt bending, or even breaking.
Eye bolts are also known in which the supporting bolt provided with a threaded shaft is accommodated with a little play in an insertion opening of the lifting eye and is held there rotatably (DE 93 16 475 U1). Therefore for multistrand or lateral applications only such so-called “rotatable” eye bolts are recommended. However, when they are installed or removed, it is necessary to use an additional tool (usually an Allen key) which then has to be stored again separately after installation or removal, wherein there is the danger that this key will be lost or mislaid.
An eye bolt of the type named at the beginning is known from EP 0 654 611 A1. However, this also requires the use of its own tool to turn the screw during installation or removal. In addition to a separate storage of the tool, however, this document also describes the possibility of coupling the tool with the lifting eye of the eye bolt such that a screwing movement can thus be introduced into the supporting bolt via the lifting eye, and when not in use, when it is not engaged with the supporting bolt, of suspending the tool captively on the eye bolt. However, the tools described there protrude significantly onto the outside of the lifting eye both when engaged with the supporting bolt and when not engaged with the latter, which is why there is the danger, when used in a confined space, that the outwardly projecting part of the tool catches on an item located in the confined space when the eye is rotated, and then a further rotation of the lifting eye to screw in the supporting bolt may possibly be blocked. In addition, the embodiments shown there for tools coupled with the lifting eye are not completely closed, with the result that, because of the elasticity of the material used for the tool, it is possible to widen the opening present in each case to such an extent that the screwing tool can be separated from the lifting eye or also subsequently connected to it. However, this also entails the danger that, due to the elasticity of the material, the tool and the lifting eye can unintentionally become separated as a result of an external effect on the tool.